Miller was arrested in 2002 for her involvement in a protest known as the Seven Year Squat. The squat consisted of an occupation of an abandoned privately owned building at 246 Gilmour Street in Ottawa by "anti-poverty Activists, homeless youth and anti-G8 protestors." The squat was so named because of the reported seven-year delay faced by those on a waiting list for subsidized housing in Ottawa. Police used tear gas to force protesters to leave the building.

After her arrest, Miller and her co-defendants mounted a defence which consisted of necessity and Colour of right. In a 2004 interview, Miller explained: "How much do we tolerate direct action as a society? And that was our big defence. What do we tolerate? We’re going to get so upset about people taking over an abandoned house and using it, and in the same blink of an eye, we tolerate how many homeless people sleeping in our streets every night?"

Myths for Profit (2009) was Miller's feature directorial debut. The film's narrative is structured around debunking three myths about Canada's role in the world. It uses interviews and animations to argue that Canada is not a "global good guy". Miller embarked on a nine-week tour, holding screenings in 45 communities across Canada.

Miller was the subject of heated controversy during the 2010 G20 protests after she told journalists about treatment of detained women by police officers. In a press conference held after she was released Miller told journalists that she and other women had been threatened with rape. She said that some detained women had been sexually assaulted. In a meeting of the parliamentary Standing Committee on Public Safety and National Security, Amy's testimony was referenced by Member of Parliament Maria Mourani: "She was told that they would have a lot of 'fun with her' and that she would never want to come to Toronto again."